The invention relates to knock sensors, and more specifically to a knock sensor having a two-piece sleeve assembly.
Knock sensors are used to detect when an engine is burning fuel in an uneven manner, a condition commonly known as xe2x80x9cknocking.xe2x80x9d Knock sensors are commonly mounted on a vehicle engine block adjacent the intake manifold or a cylinder head, where vibrations associated with knocking are transmitted through the engine block and can be detected by the sensor. Conventional knock sensors include a one-piece sleeve assembly for retaining the sensor components in relative compression. Typical knock sensor components include a piezoelectric transducer disposed between a pair of terminals. The terminals are, in turn, disposed between a pair of insulators. Knock sensors are usually bolted to the engine block using a separate bolt that passes through an aperture formed in the sleeve assembly. The bolt is then received in a threaded bore formed in the engine block. A nut is threaded onto the sleeve assembly and tightened to compress the knock sensor components to a desired load prior to molding.
Manufacture of conventional one-piece knock sensor sleeves can involve substantial machining, including threads for the nut and mating aperture within the sleeve for the bolt. Moreover, because a one-piece sleeve design is typically of T-shaped cross section, material must be removed from a workpiece to form the sleeve assembly.
A knock sensor according to the present invention to be associated with a vehicle engine includes a base and a support member press-fit into the base to define a sleeve assembly. At least one knock sensor component sheathes a portion of the support member. The support member further includes means associated therewith for maintaining the at least one knock sensor component in a predetermined relationship to the base. The support member can take various forms, including a hollow tube or a bolt-like member.
The maintaining means associated with the support member can include a lip formed on an end of the support member opposite the base and a disk spring positioned between the lip of the support member and the at least one knock sensor component.
The knock sensor of the present invention can include means for securing the sleeve assembly to an engine block. The securing means can be a separate fastener, such as a bolt. Alternatively, the securing means can be integral with the support member, thereby eliminating the need for a separate fastening means to secure the sensor to the engine block.
In another aspect of the invention, an engine control system includes a microprocessor, an ignition system electrically connected to the microprocessor and a knock sensor including a two-piece sleeve assembly electrically connected to the microprocessor. According to the present invention of the engine control system, the two-piece sleeve assembly is defined by a press-fit joint.
According to another aspect of the invention, a method for manufacturing a knock sensor associated with a vehicle engine includes providing a base having an aperture for press-fit engagement with an support member, press-fitting an support member within the aperture of the base to define a sleeve assembly. The method of manufacture can further include placing at least one knock sensor component about the member. The method of manufacture can include providing an support member having means associated therewith for retaining the at least one knock sensor component in a predetermined relationship to the base.